Like the title says, this is my first attempt at an SCP. Feel free to brutally criticize as you see fit.
My immediate, rather blunt, thoughts on the draft are a) you have an excellent command of tone and grammar, and b) it's wasted on this object. A cup that boils water, then boils your bodily fluids if you drink it. I don't see a hook. The idea can probably be adjusted to be more functional; I'll leave it to others to offer suggestions on that front.
What I was trying to say wasn't that the item boils your bodily fluids, rather that it causes any liquid the drinker touches after drinking it to boil. Should rewrite it so that points more clear, or is that also not interesting enough?
Killer coffee cup. I don't think the concept will work. A coffee cup that does something else might be interesting. If it made you much smarter for 2 hours after you drank from it but slowly turned you amoral after prolonged use it would be much more complicated and maybe better. Perhaps it just makes people want to steal it. When they use it later they slowly develop kleptomania. I am not saying these are good ideas, just different from "use it once, you die."